The Cervo (Piedmontese: Sar or Serv) is a 65-kilometre (40 mi) torrent (a form of seasonally intermittent stream) in the Piedmont region of north-west Italy.

From the Lago della Vecchia it flows rapidly through a large number of communes of the Valle del Cervo.

Close to Tollegno it receives the torrent Oropa from the right then crosses the eastern part of the city of Biella, in particular the quarter of Chiavazza.

In this section of its course the Cervo is united with a number of modest tributaries: the Mologna, the Chiebbia, the Lu Rialet and the Bruma.

Near the town of Cossato the flow grows visibly when the torrent is joined from the left by the Strona di Mosso.